Home plmn search method of mobile terminal

ABSTRACT

A Home Public Land Mobile Network (Home PLMN) search method of a mobile terminal is disclosed. The method includes determining whether an input continued for a preset period of time from a user is generated on a specified item located in a predetermined area of an idle screen, comparing a PLMN service area in which the mobile terminal is located with a Home PLMN of the mobile terminal when the input is generated as a result of the determination, and searching for the Home PLMN when the PLMN service area is not identical to the Home PLMN, and registering the searched Home PLMN so as to match the searched Home PLMN with an input of the specified item, and initializing a timer set for a Home PLMN search.

PRIORITY

This application claims the benefit under 35 U.S.C. §119(a) of a Koreanpatent application filed in the Korean Industrial Property Office onOct. 22, 2009, and assigned Serial No. 10-2009-0100783, the entiredisclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a roaming service using a mobileterminal. More particularly, the present invention relates to a HomePublic Land Mobile Network (PLMN) search method of a mobile terminal forrapidly performing a location registration in a Home PLMN or preferredroaming network by a touch on a touch screen of the mobile terminal whenfrequent movement through border areas sharing borders occurs.

2. Description of the Related Art

With the rapid globalization of the mobile industry, roaming contractsare made between providers of many countries. Accordingly, the user canreceive a service that enables the user to use his/her own terminal witha Universal Subscriber Identity Module (USIM) or Subscriber IdentityModule (SIM), without any change, even when the user has moved intoanother country. Such a service is called a “roaming service.” Theroaming service enables a subscriber to use a mobile communicationservice in an authorized network only if the subscriber has a legalInternational Mobile Subscriber Identity (IMSI).

A communication terminal receiving such a roaming service storesinformation on a Home Public Land Mobile Network (PLMN) to which thecorresponding subscriber has joined and information on a last registeredPLMN in which the communication terminal has been last used in a USIM orSIM. When the communication terminal is powered on, the communicationterminal acquires a system information message using a frequency of amaximum reception strength, extracts PLMN information from the systeminformation message, and compares the extracted PLMN information withthe last registered PLMN information. When the extracted PLMNinformation is not identical to the last registered PLMN information,the communication terminal recognizes that the current state is a statein which international roaming is required, and performs a locationregistration procedure for a base station of an adjacent cell using theextracted PLMN information, so that the communication terminal receivesan international roaming service.

However, upon performing the roaming service between European countriessharing borders, whenever a communication terminal enters a Home PLMN ora mobile communication network roaming-agreed with the Home PLMN, it isnecessary to ensure a period of time to search for the Home PLMNinformation and last registered PLMN information. As a result, frequentmovement through border areas increases roaming charges.

In addition, when the user attempts to forcibly change a locationregistration through a menu in order to reduce the roaming charges, theuser must click many times in order to execute a corresponding functiondue to a large number of entries in the menu. Therefore, the procedureof allowing the user to directly change a location registration using amenu also has a problem in that unnecessary time consumption occurs.

SUMMARY OF THE INVENTION

As aspect of the present invention is to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention provides a method for rapidly performing a locationregistration only by one touch on a Public Land Mobile Network (PLMN)search item displayed in an idle screen of a mobile terminal having atouch screen by displaying the PLMN search item in the idle screen,checking if a touch input by the user is applied to the PLMN searchitem, comparing PLMN information of an area in which the mobile terminalis located with Home PLMN information when the touch input is applied,and performing a location registration in the Home PLMN or preferredroaming network.

In accordance with an aspect of the present invention, a Home PLMNsearch method of a mobile terminal is provided. The method includesdetermining whether an input continued for a preset period of time froma user is generated on a specified item located in a predetermined areaof an idle screen, comparing a PLMN service area in which the mobileterminal is located with a Home PLMN of the mobile terminal when theinput is generated as a result of the determination, and searching forthe Home PLMN when the PLMN service area is not identical to the HomePLMN, and registering the searched Home PLMN so as to match the searchedHome PLMN with an input of the specified item, and initializing a timerset for a Home PLMN search.

In accordance with another aspect of the present invention, a method ofsearching for a Home PLMN is provided. The method includes, whenreceiving a predetermined input signal from a user, determining whethera current PLMN in which the user's mobile terminal is operating isidentical to a Home PLMN of the user's mobile terminal; when the currentPLMN is not identical to the Home PLMN, searching for the Home PLMN; andwhen the Home PLMN is found, registering the found Home PLMN andmodifying a user interface displayed on the user's mobile terminal suchthat a user interface item corresponding to the predetermined inputsignal is associated with the Home PLMN.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiment of the present invention will be more apparent fromthe following description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a view showing a case where a mobile terminal, to which a HomePublic Land Mobile Network (Home PLMN) search method of the mobileterminal according to an exemplary embodiment of the present inventionis applied, moves into a border area; and

FIG. 2 is a flowchart illustrating the entire flow of the Home PLMNsearch method of the mobile terminal according to an exemplaryembodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding, but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention are provided for illustration purposes only and notfor the purpose of limiting the invention as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

A mobile terminal explained in the following description corresponds toa complex terminal receiving a communication service through awired/wireless public network, but exemplary embodiments of the presentinvention are not limited thereto. The mobile terminal according to anexemplary embodiment of the present invention may be a mobilecommunication terminal, and may be any information communication deviceor multimedia device, such as a digital broadcasting terminal, aPersonal Digital Assistant (PDA), a smart phone, a 3G terminal, and thelike, or may be an application thereof. The 3G terminal includes, forexample, an International Mobile Telecommunication 2000 (IMT-2000)terminal, a Wideband Code Division Multiple Access (WCDMA) terminal, aGlobal System for Mobile communication/General Packet Radio Service(GSM/GPRS) terminal, and a Universal Mobile Telecommunication Service(UMTS) terminal.

The mobile terminal described below may include a USIM or SIM module,can perform a voice/image communication and/or data communication with acounterpart through a communication network, and may transmit aninternational roaming request signal to a switching system through thecommunication network when international roaming is requested; and thecommunication network functions to ensure the mobility of the mobileterminal, includes a base station and a base station controller, andsupports both synchronous and asynchronous communications.

FIG. 1 shows a case where a mobile terminal, to which the Home PublicLand Mobile Network (Home PLMN) search method of the mobile terminalaccording to an embodiment of the present invention is applied, movesinto a border area.

Referring to FIG. 1, a first PLMN service area 110 and a second PLMNservice area 120 have an overlapping border area 114. When the mobileterminal 100 moves into the border area 114, a roaming from the firstPLMN service area 110 to the second PLMN service area 120 is performed.When the mobile terminal 100 moves into the border area 114 in which thefirst PLMN service area 110 and second PLMN service area 120 overlap,and the user applies an input to a specified item located at apredetermined position of an idle screen of the mobile terminal 100 fora preset period of time, as shown in FIG. 1, the PLMN of the first PLMNservice area 110, in which the mobile terminal 100 is currently located,is compared with a Home PLMN of the mobile terminal 100. The Home PLMNis searched for when the two PLMNs are not identical to each other.

The specified item may have an indication representing “PLMN.” When theuser applies a tapping input or a long touch input continued for apreset period of time to the specified item marked with “PLMN”, whichare expressed in the idle screen of the mobile terminal 100, as shown inFIG. 1, the PLMN of a currently located service area is compared with acorresponding Home PLMN to determine whether the two PLMN are identicalto each other, and then the Home PLMN is searched for depending on aresult of the comparison. The user may apply the input via a finger, atouch pen, or the like.

The PLMN represents an identification number of a mobile communicationnetwork, that is, a mobile communication provider, and refers to apreferred network capable of providing a roaming service among PLMNs ofproviders who have contracted a roaming agreement with the provider ofthe Home network provider of the user of the mobile terminal 100. TheHome PLMN refers to a communication provider's network to which themobile terminal 100 has joined, or a network having contracted a roamingservice agreement with the communication provider's network to which themobile terminal 100 has joined.

When the mobile terminal 100 moves into the border area 114, or when themobile terminal 100 is powered on, a last registered PLMN and a HomePLMN are searched for. In this case, when the mobile terminal 100 uses acommunication provider's network called “A” in the first PLMN servicearea 110, and arrives at the second PLMN service area 120 via the borderarea 114, the last registered PLMN of the mobile terminal 100corresponds to the first PLMN service area 110.

In addition, the last registered PLMN is a network having the highestpriority in a preferred roaming network list when the mobile terminal100 is driven or when the mobile terminal 100 moves from the first PLMNservice area 110 to the second PLMN service area 120 via the border area114, as shown in FIG. 1. The preferred roaming network list may bestored in the SIM or USIM of the mobile terminal 100. The preferrednetwork list is a list of preferred networks recorded in the SIM or USIMby a network operation of a Home PLMN, to which the user of the mobileterminal 100 has joined. The network selected to have a highest prioritymay be a network having a carrier with a highest priority. A Home PLMNsearch method of the mobile terminal according to an exemplaryembodiment of the present invention is described below with respect toFIG. 2.

FIG. 2 is a flowchart illustrating the entire flow of the Home PLMNsearch method of the mobile terminal according to an exemplaryembodiment of the present invention.

Referring to FIG. 2, a plurality of items are displayed in an idlescreen of the mobile terminal in step 208. In step 210, it is determinedwhether an input continued for a preset period of time by the user isapplied to a specified item, which is located in a predetermined regionof the idle screen. The specified item represents an item marked with“PLMN,” and it is determined whether, for example, a tapping input or along touch input continued for a preset period of time using a user'sfinger, a touch pen, or the like is applied to the specified item markedwith “PLMN” expressed in the idle screen of the mobile terminal.

When it is determined in step 212 that a user input is applied to thePLMN item, a PLMN service area in which the mobile terminal is currentlylocated is compared with a Home PLMN service area to which the user ofthe mobile terminal has joined, in step 214 in order to determine if thetwo PLMN service areas are identical to each other.

When it is determined in step 216 that the PLMN service area is notidentical to the Home PLMN service area as a result of the comparison,the procedure proceeds to step 218, where a corresponding Home PLMN ofthe mobile terminal is searched for. The network of a predetermined PLMNservice area, which includes a base station and a base stationcontroller and functions to ensure the mobility of the mobile terminal,determines whether the predetermined PLMN service area corresponds tothe corresponding Home PLMN of mobile terminal, and searches for theHome PLMN in order to provide an international roaming service when thepredetermined PLMN service area does not correspond to the correspondingHome PLMN. In this case, the Home PLMN represents a communicationprovider's network to which the mobile terminal 100 has joined, or anetwork having contracted a roaming service agreement with thecommunication provider's network to which the mobile terminal 100 hasjoined.

When a corresponding Home PLMN is found as a result of the search instep 218, the procedure proceeds to step 222, where the searched HomePLMN is registered so as to correspond to the specified item, i.e. thePLMN item, located within the idle screen of the mobile terminal.Thereafter, in step 224, a timer set for the Home PLMN search isinitialized.

When a user input is not applied to the PLMN item as a result of thedetermination in step 210, the procedure returns to step 208, where itis determined whether a user input is applied to the idle screen. Whenthe PLMN service area is identical to the Home PLMN as a result of thecomparison in step 214, the procedure returns to step 208 so that theaforementioned procedure is again performed.

When searching for a corresponding Home PLMN of the mobile terminalfails in step 218, the procedure proceeds to step 220, where a PLMN issearched for based on priorities set in the SIM or USIM. The prioritiesset in the SIM or USIM are identified by a preferred roaming networklist recorded in the SIM or USIM by a network operation of a Home PLMNto which the user of the mobile terminal has joined. Generally, when amobile terminal moves into a border area in which a plurality ofcommunication networks overlap, or when the mobile terminal is poweredon, the mobile terminal searches for a last registered PLMN and a HomePLMN. In this case, when the mobile terminal uses a communicationprovider's network called “A” in a first PLMN service area, and arrivesat a second PLMN service area via a border area, the last registeredPLMN of the mobile terminal corresponds to the first PLMN service area.

The last registered PLMN may be a network having a highest priority in apreferred roaming network list set in the SIM or USIM of the mobileterminal. This is because the preferred roaming network list accordingto an exemplary embodiment of the present invention may correspond to alist of preferred networks recorded in the SIM or USIM by a networkoperation of a Home PLMN, to which the user of the mobile terminal hasjoined, and a network selected to have a highest priority is a networkhaving a carrier with a highest priority.

The operation of searching for the Home PLMN of the mobile terminalaccording to an embodiment of the present invention may be implementedas described above. According to exemplary embodiments of the presentinvention, a PLMN search item is displayed in the idle screen of amobile terminal having a touch screen, and a searched Home PLMN orpreferred roaming network is registered and connected to the PLMN searchitem, so that the user can easily and rapidly perform a locationregistration in a Home PLMN or preferred roaming network only by onetouch on the PLMN search item displayed in the idle screen, although theamount of communication increases due to frequent movement throughborder areas. Accordingly, a roaming service can be provided easily.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

1. A Home Public Land Mobile Network (Home PLMN) search method of amobile terminal, the method comprising: determining whether an inputcontinued for a preset period of time from a user is generated on aspecified item located in a predetermined area of an idle screen;comparing a PLMN service area in which the mobile terminal is locatedwith a Home PLMN of the mobile terminal when the input is generated as aresult of the determination, and searching for the Home PLMN when thePLMN service area is not identical to the Home PLMN; and registering thesearched Home PLMN so as to match the searched Home PLMN with an inputof the specified item, and initializing a timer set for a Home PLMNsearch.
 2. The method as claimed in claim 1, further comprising:searching for a PLMN based on priorities set in a correspondingSubscriber Identity Module (SIM) when the searching for the Home PLMNfails, and performing a location registration in the searched PLMN. 3.The method as claimed in claim 1, wherein the specified item indicates acorresponding PLMN of the mobile terminal.
 4. The method as claimed inclaim 2, wherein the priorities set in the SIM represent an order ofpreferred roaming networks recorded in the SIM by a network operation ofa Home PLMN, to which the mobile terminal has joined.
 5. The method asclaimed in claim 1, wherein the determining of whether the input isgenerated is performed according to a tapping operation of the userusing a touch screen of the mobile terminal.
 6. The method as claimed inclaim 1, wherein the Home PLMN corresponds to either a communicationprovider's network to which the user of the mobile terminal has joined,or a network contracting a roaming service agreement with a provider ofthe communication provider's network, to which the user of the mobileterminal has joined.
 7. A method of searching for a Home Public LandMobile Network (PLMN), the method comprising: when receiving apredetermined input signal from a user, determining whether a currentPLMN in which the user's mobile terminal is operating is identical to aHome PLMN of the user's mobile terminal; when the current PLMN is notidentical to the Home PLMN, searching for the Home PLMN; and when theHome PLMN is found, registering the found Home PLMN and modifying a userinterface displayed on the user's mobile terminal such that a userinterface item corresponding to the predetermined input signal isassociated with the Home PLMN.
 8. The method of claim 7, furthercomprising: when the Home PLMN is not found, identifying a PLMN based ona priority list stored in a Subscriber Identity Card (SIM) or UniversalSIM (USIM) in the user's mobile terminal, and modifying the userinterface based on the identified PLMN.
 9. The method of claim 7,wherein the predetermined input signal is generated when a user touchesan icon displayed in the user interface for a predetermined period oftime via a finger or stylus.
 10. The method of claim 7, furthercomprising: initializing a timer set for Home PLMN search.